I am working on a 99 Prelude with a 65mm Edelbrock TB. It has a VERY VERY loud whistle coming from the TB area. But it's hard to tell exactly where it's coming from b/c it's so loud. So I think that it's an intake leak. I spray brake cleaner at every single point in the intake tract. Nothing!

The idle fluctuates from 1000 to 1800 rpm and there's a loud whistle that stays consistantly the same pitch as the idle raises and lowers. I'm also getting P0505, which is the Idle Control System Malfunction.

I have replaced the TB gasket two times. I have checked all hoses for leaks, check the MAP for leaks, bled the coolant, reset the ECU, followed the steps in the Helms, and I still can't get anywhere.

After doing a LOT of reading on this forum, I tried to adjust the idle once again by following the correct procedure. Well, I turn the screw ALL the way in and the idle lowers and stops fluctuating. I shut the engine off and plug the IACV back in, reset the ECU, start the car and it's idling fine. It doesn't fluctuate anymore.

But the whistling is the same! The whistling is so loud, that I guarantee that everyone on this forum wouldn't drive the car. You can easily hear the car idling from a half mile away. It still whistles the same with the intake tubing and filter off the car.

Does anybody have ANY ideas where this whistling could be coming from? It's still possible I have an intake leak. I am this close to ripping the intake manifold completely off the car and putting in new gaskets. But I don't want to do that since I'm not sure it will fix the problem.

The only time I can get the whistling to quiet down somewhat is when I drive the car and get partially on the throttle at cruising speeds, where the car accelerates slightly. I would imagine that the whistling stops when there is no more vacuum on the motor.

What could be causing this insanely loud whistling at idle? Thank you in advance for your help!

 

haven't heard of this problem before. my guess is a damaged gasket?

 

Mine did that when I tried to make my own gasket and block off the Idle Air Control Valve and another hole. More than likely it is your gasket. Spray some liquid on your throttle body and you should be able to tell where it is leaking from.

 

Well, I haven't had a new OEM TB gasket. So first, I made my own out of paper gasket material. To be safe, I gopped black RTV on both sides of the material, then installed it. I have never had an intake leak result from doing this. But the whistling didn't change at all.

I sprayed brake cleaner all over the TB and there was no change in idle speed.

So I ripped the TB off again, and this time, I used a cereal box to make my gasket material. I did not bother with RTV this time. Just bolted it up and torqued it to spec. Same whistling once again!

I was hoping to get a change in tone, but I didn't. I sprayed brake cleaner on it again and there is no change in idle speed.

What do you think? The leak doesn't seem to be coming from the TB since brake cleaner didn't effect it at all.

Oh, I even removed the EGR valve and cleaned it and gooped Ultra Copper RTV on the gasket and reinstalled. No change. Oh well, worth a shot.

I also removed the IACV and made sure the leak wasn't coming from those black rings. I put black RTV around those rings and it's still whistling. It's definitely not leaking there.

Thanks for your help so far. Any other ideas? Or something you think I overlooked? I will stick the stock TB back on, which I believe has a bad TPS. I just want to see if the whistling stops with the stock TB and the stock gasket.

BTW, the stock gasket will not work with the Edelbrock TB. I either have to make your own or get the Edelbrock gasket.

 

Probably not related, but

http://www.youtube.com/watch?v=nmvjwOgVoVs

Anyway, I'm thinking it might be more on the inside of the TB. Check the butterfly for any pits around the edge, and make sure it seats properly

 

Come on man. Bubb Rubb? This Prelude doesn't have whistler tips. HAHA

I have swapped the stock TB back on there just to make sure the Edelbrock isn't causing the whistling. No change in tone. I have completely ruled out the TB now.

My next guess is the intake manifold gaskets went out. Without a smoke machine, I can't find the intake leak. The leak has to be coming from a place that I can't reach with the brake cleaner.

Also, I got the surging under control by screwing the idle screw all the way in. That lowered the idle enough to stop the surging. But the whistling is exactly the same.

Thanks for trying. Any other ideas? If I happen to fix it, I'll be sure to post for searching purposes.

 

I know this is old as hell, but was this problem ever solved???... got a similar whistle with the jdm h22a in the lude... Only whistles at idle, and I don't think it's as loud... guess I need to keep looking for a leak... no luck caused me to perform this search

 

ok guys ive had this problem and fixed it, take off ur cold air/whatever pipe, and inside the throttle body there are 2 holes right? they suck air, plug one with ur finger, prolly top one, if the engine dies to normle idle and whistle goes away then ur iacv is not closing all the way, either block it off or replace it, thats if u cant make the adjustments,

 

thanks